Despite his record as an instigator of a bloody crackdown on left-wing students in 1976, Mr Samak has blown hot and cold against the protest, threatening variously the "full force of the police", a siege, or nothing at all.

The protesters accuse Mr Samak of being a puppet of former Prime Minister Thaksin Shinawatra, ousted by a military coup in 2006.

Mr Samak has repeatedly changed his approach to the protesters - prevaricating between advocating a "softly, softly" approach and vowing to take a harder line.

The protests began on Tuesday, when more than 30,000 people took to the streets in a well-co-ordinated action.

They have been called by a group calling itself the People's Alliance for Democracy - formed three years ago as a movement to bring down Mr Thaksin.